This invention relates to fittings for connecting electrical metallic tubing (EMT) to a panel and specifically to an improved fitting that allows EMT to be snap fitted into the fitting to provide a quick and easy connection to a panel.
Historically, electrical metal tubing (EMT) was connected to electrical boxes by a tubular fitting including a leading end with a threaded nose for insertion into a circular aperture in the box and a trailing end including a screw mounted laterally through the fitting wall for securing the EMT to the fitting. This arrangement, although providing an adequate means for securing EMT to boxes, junctions, and various electrical housings, is time consuming. For every connection, an installer must first stab the leading end of the fitting into the box and thread a lock nut onto the threaded nose to secure the fitting to the box and, secondly, secure the EMT to the trailing end of the fitting by tightening the laterally mounted screw through the fitting wall. For any given installation of EMT in a building or factory, electrical contractors may be required to make hundreds or even thousands of such connections to completely wire the building. Additionally, tools must typically be used to achieve a secure connection, including a wrench on the lock nut and a screw on the laterally mounted screw. Therefore, it should be appreciated that completing all of these connections can be very time consuming, with the contractors typically using both a wrench and a screwdriver on each connection.
Recently, snap engagement fittings have become popular as a means of connecting cables or EMT to electrical junction boxes. One such type of snap fitting is disclosed in U.S. Pat. No. 5,373,106 (hereinafter the ""106 patent) issued Dec. 13, 1994, and entitled xe2x80x9cSnap In Cable Connectorxe2x80x9d. This patent disclosed a quick connect fitting for an electrical junction box including a split ring member that improved the ease of use and reduced the time involved in securing electrical fittings to electrical junction boxes. However, the fitting of the ""106 patent included the traditional method of securing the EMT or cable to the trailing end of the fitting, thereby requiring the use of a screwdriver to complete the connection on the trailing end.
Although inclusion of a split ring on the leading end of the fitting in the ""106 patent reduced installation time for the fitting to the box, it did not reduce installation time at the trailing end of the fitting, in which the EMT is secured to the fitting in the traditional manner. Therefore, what is needed is a fitting for securing EMT to panels and the like that does not require the use of any tools, at either the leading or trailing end, and that allows the leading end to be snap fitted into the panel and the EMT to be snap fitted into the trailing end. A fitting that allows snap engagement at both ends of the fitting, without the use of tools, would vastly reduce the time involved for installing EMT in a structure. Additionally, the fitting should be designed to work with standard electrical panels, boxes, housings, etc., including snap fit engagement with standard size knockout apertures.
These and other advantages will become apparent by reading the attached specification and claims in conjunction with reference to the attached drawings.
The present invention comprises a fitting that provides a trailing end designed for snap-in engagement of EMT. The fitting comprises a hollow, tubular, electrically conductive electrical connector having a leading for connecting to a panel and a trailing end for connecting to EMT. A fastening arrangement is provided on the leading end to allow snap-in engagement to a panel. A resilient, electrically conductive, cylindrical-shaped split ring is secured within the trailing end of the connector. A plurality of locking tangs are lanced longitudinally and bent inwardly to a smaller diameter than the outer diameter of EMT that the fitting will be used in conjunction with. Arcuate edges are included on the leading ends of the locking tangs. The arcuate edges are capable of digging into the outer surface of the EMT and holding it fast to the trailing end of connector. The fastening arrangement on the leading end of the fitting is typically a split ring affixed to the nose of the connector. The connector, split ring affixed to the nose of the connector, and the split ring secured within the trailing end of the connector comprise the fitting of the present invention that provides snap-in engagement on both ends of the fitting. The fitting allows the leading end of the connector to be snapped into a standard sized aperture in a panel and also allows EMT to be snapped into the trailing end of the fitting. The large contact area between the locking tangs and the EMT provide a large amount of surface contact between the locking tangs and the EMT, thereby improving continuity and lowering the millivolt drop.